Heat sealing station

ABSTRACT

A heat sealing station for laminating superimposed elongate webs of material including an upper heat seal unit and a lower pressure platen in vertical registry, the lower pressure platen having vertical reciprocal motion below the web and the upper heat seal unit having vertical reciprocal motion above the web, the upper heat seal unit further being characterized by resilient mounting construction to cooperate with and to absorb the forces generated by operation of the lower pressure platen.

llnited States Patent ichols [451 Apr. 118, 11972 [54] HEAT SEALINGSTATION Primary ExaminerDouglas J. Drummond Attrney-Necho and Kimmelman[72] Inventor: Matthew Nichols, Nornstown, Pa. [73] Assignee: SauterPackaging Company, Souderton, [57] ABSTRACT Pa. A heat sealing stationfor laminating superimposed elongate [22] Filed, June 23 1970 websofmaterial including an upper heat seal unit and a lower pressure platenin vertical registry, the lower pressure platen [2]] Appl. No.: 49,002having vertical reciprocal motion below the web and the upper heat sealunit having vertical reciprocal motion above the web, the upper heatseal unit further being characterized Cl 3, 100/264, 0/ P by resilientmounting construction to cooperate with and to [51] Int. Cl. ..B30b /34,83% 5/00 absorb the forces generated by operation of the lower pressure[58] Field of Search ..156/583; 100/264. 93 P platen.

[ 56] References Cited 14 Claims, 8 Drawing Figures UNITED STATESPATENTS 3,577,304 5/1971 Guyer ..156/580 PATENTEDAPR 18 I972 SHEET 2 BF4 /0 12 1 E I 38 w m W/Awa MATTHEW HEAT SEALING STATION BACKGROUND OFTHE INVENTION The present invention relates to the general field ofmedicinal tablet packaging, and more particularly, is directed to a heatsealing station capable of sealing medicinal tablets or the like withincontinuous strips of laminated material.

In the interest of sanitation, speed, accuracy and inventory control, ithas been increasingly the practice in institutions such as hospitals andnursing homes to utilize medicinal tablets sealed in blisters formed ina continuous strip of thermoplastic material. It is the usual procedureto pre-form a plurality of spaced blisters in a strip of thermoplasticmaterial to receive the medicinal tablets individually therein. Afterfilling, a strip of foil sheet is usually laminated to the top of thethermoplastic strip to seal the medicinal tablets within thethermoplastic blisters. The foil layer acts as a readily frangibleclosure to permit easy access to the medicinal tablets when desired foruse. A heat responsive adhesive is generally employed to affix the foillayer to the thermoplastic layer. Prior workers in the field haveexperienced difficulty in designing and fabricating heat sealingequipment capable functioning at rates sufficient to handle the effluentfrom high speed medicinal tablet feeding apparatus presently availableas exemplified by my co-pending application entitled Apparatus forPackaging Medicinal Tablets or the Like, Ser. No. 26,616 filed Apr. 8,1970.

SUMMARY OF THE INVENTION The present invention relates generally to anapparatus designed to seal continuous webs of materials and moreparticularly, is directed to a heat sealing station designed to affix anelongate strip of foil material to the top surface of an elongate stripof thermoplastic material by activating an intermediate heat responsiveadhesive layer.

The instant heat sealing station includes a lower pressure platen whichis vertically reciprocal at right angles to and below the plane oftravel of the elongate web of material. The pressure platen serves topress the foil layer and the thermoplastic layer upwardly against theupper heat seal unit to activate the heat sensitive adhesive to therebyaffix the foil and thermoplastic strips. The pressure platen is providedwith easily interchangeable platen plates which are designed withsuitable hole patterns to accommodate various thermoplastic blisterpackage configurations.

The upper heat seal unit includes a heat seal block with integral heaterelements and resilient mounting construction. The heat seal blockapplies directly against the top surface of the upper foil strip andemploys sufficient heat to fuse the adhesive layer by radiation throughthe foil material. The resilient mounting serves to absorb the shocks ofrepeated pressure contacts of the lower pressure platen resulting fromthe said reciprocating action.

The heat seal unit further includes stationary refrigeration means toprecisely define the area of heat scaling in cooperation with thecombined action of the lower pressure platen and the heat seal block.The upper seal unit includes air cylinder means which function tovertically elevate the heater from the top surface of the foil followingthe sealing operation to thus quickly pull the heater-from the webmaterial following the precise application of sufficient heat foradhesive sealing puroses. p It is therefore an object of the presentinvention to provide an improved apparatus for heat sealing elongatestrips of the type set forth.

It is another object of the present invention to provide a novel heatsealing station including a vertically reciprocal lower pressure platenand a vertically reciprocal upper heat seal unit, the said heat unit andpressure platen functioning in vertical registry above and belowelongate strips of superimposed materials.

It is another object of the present invention to provide a novel heatsealing station incorporating a lower pressure platen which isvertically reciprocal against an upper heat seal unit, the heat sealunit being resiliently mounted to receive cyclical pressure from thelower pressure platent.

It is another object of the present invention to provide a novel heatsealing station including a lower pressure platen for use with a stripof thermoplastic material having pre-formed blisters dependingtherefrom, the pressure platen including a patterned surface tocooperate with and to receive the depending blisters during the heatsealing operation.

It is another object of the present invention to provide a novel heatsealing station including opposed lower pressure platen means and upperheat seal means in vertical juxtaposition, each of the said pressureplaten means and heat seal means being provided with respectivevertically reciprocating means.

It is a further object of the present invention to provide a novel heatsealing station incorporating upper heat seal means including a heaterblock which is vertically reciprocal with respect to adjacent, fixed,refrigeration units.

It is another object of the present invention to provide a novel heatsealing station incorporating an upper, resiliently mounted heat sealunit, the resilient construction including easily changeable springs tocontrol sealing pressure.

It is another object of the present invention to provide a novel heatsealing station that is rugged in construction, simple in design andtrouble-free when in use.

Other objects and a fuller understanding of the invention will be had byreferring to the following description and claims of a preferredembodiment thereof, taken in conjunction with the accompanying drawingswherein like reference characters refer to similar parts throughout theseveral views and in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end elevation view of thedevice looking upstream.

FIG. 2 is a cross sectional view taken along Line 22 of FIG. 1, lookingin the direction of the arrows.

FIG. 3 is a cross sectional view taken along Line 3-3 of FIG. 2, lookingin the direction of the arrows.

FIG. 4 is a partial, side elevational view taken along Line 4--4 of FIG.1, looking in the direction of the arrows.

FIG. 5 is a partial, top plane view taken along Line 55 of FIG. 4,looking in the direction of the arrows.

FIG. 6 is a schematic, end elevational view of the apparatus showing thecondition while the web material to be sealed is in motion.

FIG. 7 is a schematic, end elevational view of the apparatus showing theposition of parts when the web material is being sealed.

FIG. 8 is a schematic, end elevational view of the apparatus showing therelative position of parts when the machine is stopped.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION Althoughspecific terms are used in the following description for the sake ofclarity, these terms are intended to refer only to the particularstructure of my invention selected for illustration in the drawings andare not intended to define or limit the scope of the invention.

Referring now to the drawings, I show in FIG. 1 an apparatus generallydesignated 10 for heat sealing elongate strips of material. A fixedframe 12 carries a lower pressure platen 14 and an upper heat seal unit16 which arrange in vertical juxtaposition for heat sealing purposes.Both the pressure platen l4 and heat seal unit 16 are provided withmeans for vertical reciprocation with respect to the stationary frame 12to heat seal the elongate strip 18 which comprises a lower,thermoplastic web 96, an upper foil web 102 and an intermediate layer ofheat sensitive adhesive 108. The lower pressure platen l4 reciprocatesfrom a lower position 20 as illustrated in FIGS. 1, 2, 6 and 8 to anupper, pressure sealing position 22 as illustrated in FIG. 7. A cylinder24, which may be of the usual hydraulic or pneumatic type, journals tothe frame 12 through the bushing 40 to reciprocate the lower pressureplaten 14 by means of the piston rod 26, the piston rod pin 42 and thecrank 28. The lower platen link 30 extends from the crank 28 pivotallyconnects to a stationary portion of the frame 12 through a pivot pin 32.The lower platen links 30 is responsive to action of the piston rod 26through the crank pivot pin 34 and the piston rod pivot pin 42. Theupper platen link 36 pivotally connects to the lower platen link 30 andthe crank 28 at the crank pivot pin 34 and transmits verticalreciprocating forces to the lower pressure platen 14 through the bushing110 which secures upon the upper pivot pin 38 in the usual manner. Thus,activation of the cylinder 24 causes resulting reciprocating motion inthe lower pressure platen 14. It will be observed that the platen l4vertically moves through a distance of approximately one inch to pressthe strip material 18 against the lower surface 88 of the heat seal unit16. The operation of the cylinder 24 functions to successively push andpull the piston rod 26 to thereby reciprocate the platen 14 with respectto the frame 12. The bushing 40 affixes in the frame 12 and permits thecylinder 24 to pivot about the frame as required to compensate for theslight elevating effect of the combined crank 28 and lower platen line30 as they pivot about the lower pivot pin 32.

The use of the lever action through the crank 28 and the upper and lowerplaten links 36, 30 combine to gain tremendous pressure for sealingpurposes utilizing only a relatively small hydaulic cylinder 24. Thepositioning of the parts as illustrated generate great pressures whenthe linkage reaches its uppermost position due to the mechanicaladvantage while requiring the expenditure of only minimum amounts ofhydraulic fluid.

The heat seal unit 16 positions vertically above the lower pressureplaten 14 and is vertically reciprocal with respect to the frame 12. Anupper cylinder 44 of the hydraulic or pneumatic type journals within theframe 12 by means of the upper cylinder bushing 46 andreciprocates itspiston rod 48 in the usual manner. The piston rod 48 pivotally connectsto the crank 50 through the piston pivot pin 52 to thereby impartgenerally horizontally reciprocating motion to the crank 50 uponfunction of the upper cylinder 44. The crank pivotally connects to theupper heat seal links 54, 54 at the respective pivot pins 56, 56' tothereby rotate the links 54, 54 about the upper pivot pins 58,58 whichaffix to the upper crosshead 68. The lower heat seal unit links 60, 60pivotally affix to the crank 50 and respective to the upper heat sealunit links 54, 54 through the pivot pins 56, 56'. The links 60,60terminate downwardly in pivotal connections to the lower crossheads 76at the respective lower pivot pins 62, 62. Operation of the cylinder 44pushes the crank 50 to pivot the respective links 54, 60 and 54', 60about the pivot pins 58, 58 to raise the heat seal unit 16. Downwardmovement of the upper crosshead 68 and its connected frame block 112 isprevented by the frame affixed threaded studs 114 and the nuts 116.Thus, activation of the cylinder 44 serves to vertically reciprocate theheat seal unit 16 through the piston rod 48, the crank 50, the action ofthe upper links 54, 54 and the lower links 60,60.

The heat seal unit 16 is reciprocal from a lower, heat sealing position64 illustrated in FIGS. 1, 2, 6 and 7 to an upper position 66 asillustrated in FIG. 8. It will be observed in FIGS. 1, 6 and 7 that therespective upper and lower heat seal unit links 54, 54' and 60, 60connect to the crank 50 in a manner to position off center when the heatseal unit 16 reciprocates to its lowermost position 64. By positioningthe respective links off center, the links provide a resiliency in theupper heat seal unit 16 when impacted by the lower pressure platen 14 asthe platen reciprocates to its upper, pressure sealing position 22. SeeFIG. 7. The upper links 54, 54' pivotally affix to the frame connectedcrosshead 68 which in turn resiliently affixes to the frame 12 throughthe block 112 and the compression springs 70. The combination of thecompression springs 70, and the knee action of the respective off centerlinkage connections 54, 60 and 54, 60' combine to completely absorb allof the shock attendant with repeated impacts against the heat seal block74 generated by the reciprocating operation of the lower pressure platen14.

The springs 70 mount above the block 112 and are readily accessible bysimply turning the top securing nuts to expose the springs. By employingheavier or weaker springs above the block 112, the sealing pressurebetween the lower pressure platen 14 and the heat seal unit 16 may beeasily adjusted. Additionally, the resilient spring construction servesto protect the upper heat seal unit 16 from damage in the event aforeign object interposed between the pressure platen and heat seal unitduring the sealing operation.

The heat seal unit 16 is provided with a plurality of spaced,longitudinally extending heating elements 72 which may be of theelectric resistance type to evenly heat the entire heat seal unit block74. As best seen in FIGS. 1 and 2, the heat seal block 74 connects thelower links 60, 60' through the lower crosshead 76 and the crossheadblock 77. A plurality of transverse grooves 78 penetrate the bottom ofthe crosshead block 77 at the connection to the heat seal block 74 tothereby minimize radiation from the block by reducing contact areabetween the blocks 74, 77. In this manner, the heat available forsealing purposes at the lower block surface 88 is maximized. Front andrear refrigerating units 80, 82 longitudinally extend adjacent to thesides of the upper heat seal unit 16 and stationarily connect to themachine frame 12 through the respective supports 84, 86 as best seen inFIGS. 1 and 3, the refrigerating units 80, 82 serve to precisely limitthe area of heat spread from the heat seal unit 16 to define the exactsealing area upon the elongate strip 18. It should be noted that theheat seal unit 16 vertically reciprocates with respect to therefrigerating units 80, 82 and when urged to its lower position 64, thelower surface 88 of the heat seal block 74 projects slightly beneath thebottom of the refrigerating units to contact the top of the strip 18 forheat sealing purposes.

Referring now to FIGS. 4 and 5, I show the lower pressure platen 14including a platen plate 90 which is provided with a plurality ofprecisely spaced recesses 92. The recesses 92 correspond in size andlocation to the depending blisters 94 which had previously been formedin the thermoplastic portion 96 of the strip material 18. In operation,the blisters 94 align directly over the platen plate recesses 92 and fitwithin the recesses when the lower pressure platen reciprocates to itsupper, pressure sealing position 22. See FIG. 7. A threaded knob 100removably, threadedly engages the pressure platen construction to lockthe pressure plate 90 therein. It will be appreciated that various sizeblisters 94 may be formed in the thermoplastic strip 96 to accommodatemedicinal tablets or capsules of different sizes. Accordingly, varioussize blisters 94 may be readily accommodated by the same equipmentsimply by providing additional platen plates 90 having recesses 92corresponding in size, shape and location to the blisters in the stripbeing sealed. Through action of interchangeable platen plates 90 andreadily engaging and disengaging construction such as the threaded knob100, the apparatus may be readily and speedily altered to accommodatevarious sized pre-formed blister strips.

In operation, a strip 18 of elongate web material, for example, an upperfoil layer 102 and a lower, blistered thermoplastic strip 96 having theblisters pre-filled with medicinal tablets are superimposed with a layerof heat sensitive adhesive 108 of any suitable, well known varietyinterposed between the layers. The strip 18 feeds into the apparatus 10across the top of the receiving table 104. The table 14 is verticallyadjustable by means of the elongate slots 106 and bolts 118 which turninto the machine frame 12 to position the strip 18 adjacent the lowersurface 88 of the heat seal block 74. An indexing mechanism (not shown),of well known design, feeds the strip 18 into the apparatus 10 inmeasured segments in response to operation of the sealing mechanism.

As best seen in FIG. 6, when initiating the sealing operation, the lowerpressure platen l4 reciprocates to its lower position 20, the upper heatseal unit 16 reciprocates to its lower, heat sealing position 64 and thestrip 18 indexes into the apparatus 10. Upon completion of the stripindexing step, the cylinder 24 activates to reciprocate the pressureplaten 14 upwardly to its upper pressure sealing position 22 throughoperation of the piston rod 26, crank 28, lower platen link 30 and theupper platen link 36. As previously indicated, the impact forcesgenerated by operation of the lower pressure platen 14 are absorbed bothby the compression springs 70 and the off set position of the heat sealunit upper and lower links 54, 54', 60, 60. With the lower pressureplaten 14 in its upper position 22 and the heat seal unit 16 in itslower position 64, the heating elements 72 function to rapidly seal thefoil layer 102 to the thermoplastic layer 96 by activating the heatsensitive adhesive 108. Immediately upon completion of the heatingcycle, the upper cylinder 44 functions to rapidly pull the heat sealunit 16 away from the sealed strip 18 through operation of the pistonrod 48, the crank 50 and the upper and lower links 54, 54 and 60, 60' toprevent damage to the sealed material. The lower cylinder 24 againfunctions to reciprocate the lower pressure platen 14 to its lowermostposition thereby separating the depending blisters 94 from the platenrecesses 92 to permit further indexing of the strip 18 through theapparatus 10. See FIG. 8. Upon lowering the upper heat seal unit 16 toits lowermost position 64 through operation of the upper cylinder 44 inthe manner hereinbefore described, the apparatus resets to its initialposition ready for indexing an additional length of material as in FIG.6.

Iclaim:

1. In a heat seal station for sealing an elongate strip of superimposedmaterials having an intermediate heat sensitive adhesive layer, thecombination of A. a frame;

B. a lower pressure platen vertically reciprocal within the frame,

I. said pressure platen being movable from a lower position to an upperposition,

2. said pressure platen being provided with reciprocating means;

C. an upper heat seal unit vertically aligned above the said lowerpressure platen,

1. said heat seal unit being reciprocal from a lower position to anupper position,

a. said upper position being out of contact with the said materialstrip,

2. said upper heat seal unit being provided with reciprocating meansand,

3. said lower pressure platen pressing a portion of the said stripagainst the heat seal unit for sealing purposes when the pressure platenmoves to its upper position and the heat seal unit reciprocates to itslower position;

and

D. resilient means absorbing the impact forces from reciprocation of thelower pressure platen into contact with the heat seal unit.

2. The invention of claim 1 wherein a portion of the resilient meansinclude a portion of the said upper heat seal unit reciprocating means.

3. The invention of claim 1 wherein the said strip contains dependingblisters and the said lower pressure platen is provided with recessmeans to receive the said depending blisters therein.

4. The invention of claim 3 wherein the recess means include a pluralityof recesses of size and location to receive the said blisters.

5. The invention of claim 1 wherein the said lower pressure platenreciprocating means include a cylinder, the said cylinder being affixedto the said machine frame.

6. The invention of claim 5 wherein the said cylinder is provided withpivoting construction to permit pivotal movement of the said cylinderwith respect to the said frame upon reciprocation of the lower pressureplaten.

7. The invention of claim 2 wherern the said upper heat seal unitreciprocating means include an upper link and a lower link pivotallyconnected together, the said upper and lower links positioning offcenter in a resilient junction to provide a portion of the saidresilient means.

8. The invention of claim 1 and stationary refrigeration means, the saidrefrigeration means precisely defining the area of upper heat seal unitoperation.

9. The invention of claim 1 wherein the upper heat seal unit includes aheat seal block containing heating elements, the heat seal blockconnecting to the reciprocating means through an intermediate crosshead,the connection between the heat seal block and the crosshead beingprovided with groove means to limit heat radiation therethrough.

10. The invention of claim 7 wherein the upper links terminate upwardlyin a pivotal connections to an upper crosshead, the said upper crossheadresiliently affixing to the said frame to provide the remainder of saidresilient means.

11. The invention of claim 1 wherein the heat seal unit reciprocates toits said lower position and the pressure platen reciprocates to itslower position when the strip indexs into the heat seal station.

12. The invention of claim 1 wherein the said upper heat seal unitreciprocates to its upper position upon completion of the sealingoperation.

13. The invention of claim 10 wherein the remainder of said resilientmeans include a plurality of compression springs interposed between thesaid crosshead and a portion of the frame.

14. The invention of claim 13 wherein the remainder of said resilientmeans incorporate means to readily change the said springs.

1. In a heat seal station for sealing an elongate strip of superimposedmaterials having an intermediate heat sensitive adhesive layer, thecombination of A. a frame; B. a lower pressure platen verticallyreciprocal within the frame,
 1. said pressure platen being movable froma lower position to an upper position,
 2. said pressure platen beingprovided with reciprocating means; C. an upper heat seal unit verticallyaligned above the said lower pressure platen,
 1. said heat seal unitbeing reciprocal from a lower position to an upper position, a. saidupper position beiNg out of contact with the said material strip, 2.said upper heat seal unit being provided with reciprocating means and,3. said lower pressure platen pressing a portion of the said stripagainst the heat seal unit for sealing purposes when the pressure platenmoves to its upper position and the heat seal unit reciprocates to itslower position; and D. resilient means absorbing the impact forces fromreciprocation of the lower pressure platen into contact with the heatseal unit.
 2. said pressure platen being provided with reciprocatingmeans; C. an upper heat seal unit vertically aligned above the saidlower pressure platen,
 2. said upper heat seal unit being provided withreciprocating means and,
 2. The invention of claim 1 wherein a portionof the resilient means include a portion of the said upper heat sealunit reciprocating means.
 3. The invention of claim 1 wherein the saidstrip contains depending blisters and the said lower pressure platen isprovided with recess means to receive the said depending blisterstherein.
 3. said lower pressure platen pressing a portion of the saidstrip against the heat seal unit for sealing purposes when the pressureplaten moves to its upper position and the heat seal unit reciprocatesto its lower position; and D. resilient means absorbing the impactforces from reciprocation of the lower pressure platen into contact withthe heat seal unit.
 4. The invention of claim 3 wherein the recess meansinclude a plurality of recesses of size and location to receive the saidblisters.
 5. The invention of claim 1 wherein the said lower pressureplaten reciprocating means include a cylinder, the said cylinder beingaffixed to the said machine frame.
 6. The invention of claim 5 whereinthe said cylinder is provided with pivoting construction to permitpivotal movement of the said cylinder with respect to the said frameupon reciprocation of the lower pressure platen.
 7. The invention ofclaim 2 wherein the said upper heat seal unit reciprocating meansinclude an upper link and a lower link pivotally connected together, thesaid upper and lower links positioning off center in a resilientjunction to provide a portion of the said resilient means.
 8. Theinvention of claim 1 and stationary refrigeration means, the saidrefrigeration means precisely defining the area of upper heat seal unitoperation.
 9. The invention of claim 1 wherein the upper heat seal unitincludes a heat seal block containing heating elements, the heat sealblock connecting to the reciprocating means through an intermediatecrosshead, the connection between the heat seal block and the crossheadbeing provided with groove means to limit heat radiation therethrough.10. The invention of claim 7 wherein the upper links terminate upwardlyin a pivotal connections to an upper crosshead, the said upper crossheadresiliently affixing to the said frame to provide the remainder of saidresilient means.
 11. The invention of claim 1 wherein the heat seal unitreciprocates to its said lower position and the pressure platenreciprocates to its lower position when the strip indexs into the heatseal station.
 12. The invention of claim 1 wherein the said upper heatseal unit reciprocates to its upper position upon completion of thesealing operation.
 13. The invention of claim 10 wherein the remainderof said resilient means include a plurality of compression springsinterposed between the said crosshead and a portion of the frame. 14.The invention of claim 13 wherein the remainder of said resilient meansincorporate means to readily change the said springs.